An engine (E) includes a crankcase body (19) including a bottom plate (19a) and a tubular portion (19c), a crankcase cover (20) covering a case opening portion (19b) of the crankcase body (19), a crankshaft (2), a cylinder base portion (21a) located inside the crankcase body (19), a cylinder block (21b) located outside the crankcase body (19), and a camshaft (25) located inside the crankcase body (19) and between the bottom plate (19a) and cylinder base portion (21a). The crankcase body (19) has the bottom plate (19a) detachably attached to the tubular portion (19c).
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1. An engine comprising:
a crankcase body including a bottom plate including a first crankshaft insertion hole and a tubular portion including a case opening portion on an opposite side to the bottom plate;
a crankcase cover including a second crankshaft insertion hole and covering the case opening portion of the crankcase body;
a crankshaft which is inserted into the first crankshaft insertion hole and the second crankshaft insertion hole;
a cylinder base portion located inside the crankcase body;
a cylinder block located outside the crankcase body; and
a camshaft disposed inside the crankcase body and between the bottom plate and the cylinder base portion, wherein
the crankcase body has the bottom plate detachably attached to the tubular portion,
a shaft portion of the camshaft is positioned between the cylinder base portion and the bottom plate, and the shaft portion of the camshaft is positioned to be pressed from above by the cylinder base portion when viewed from the upper side of the case opening portion, and
the bottom plate is configured to axially support the shaft portion of the camshaft.
2. The engine according to
the crankcase cover is detachably attached to the crankcase body.
3. The engine according to
the cylinder base portion overlaps with at least a part of the camshaft as seen from the case opening portion.
4. The engine according to
the cylinder base portion and the cylinder block form a cylinder unit; and
the cylinder unit is detachably attached to the crankcase body.
5. The engine according to
the engine includes a valve mechanism;
the valve mechanism includes:
a timing gear fixed to the crankshaft;
the camshaft rotatably supported by the bottom plate of the crankcase body;
a pair of lifters supported to be swingable on the bottom plate of the crankcase body;
a pair of rocker arms which are supported to be swingable via rocker arm shafts and one end of which abuts against an intake valve or an exhaust valve;
a pair of push rods for connecting the pair of lifters to the other ends of the pair of rocker arms; and
a pair of valve springs for urging the intake valve and the exhaust valve in a closing direction; and
the pair of push rods are accommodated in a push rod accommodation portion formed in the cylinder block.
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This application is a National Stage Patent Application of PCT International Patent Application No. PCT/JP2018/013832 (filed on Mar. 30, 2018) under 35 U.S.C. § 371, which is hereby incorporated by reference in their entirety.
The present invention relates to an engine which can be mounted on a working machine such as a lawn mower or a high pressure washer.
Generally, an engine includes a crankcase having first and second bearing portions which support both ends of a crankshaft and a cylinder into which a piston is fitted. For example, Patent Literature 1 discloses an engine in which a crankcase is formed of first and second case half bodies which are joined to each other at a dividing surface which diagonally intersects axes of first and second bearing portions and a cylinder and the first bearing portion are integrally formed on the first case half body, and further the second bearing portion is integrally formed on the second case half body.
However, in the engine structure of Patent Literature 1, there is room for improvement in workability during maintenance because the first and second case half bodies are divided by the dividing surface which diagonally intersects.
The invention provides an engine having excellent workability during maintenance.
The invention is an engine which includes:
a crankcase body including a bottom plate including a first crankshaft insertion hole and a tubular portion including a case opening portion on an opposite side to the bottom plate;
a crankcase cover including a second crankshaft insertion hole and covering the case opening portion of the crankcase body;
a crankshaft which is inserted into the first crankshaft insertion hole and the second crankshaft insertion hole;
a cylinder base portion located inside the crankcase body;
a cylinder block located outside the crankcase body; and
a camshaft disposed inside the crankcase body and between the bottom plate and the cylinder base portion, where
the crankcase body has the bottom plate detachably attached to the tubular portion.
According to the invention, the crankcase body has the bottom plate detachably attached to the tubular portion. Therefore, by removing the bottom plate from the tubular portion during maintenance, it is possible to easily replace the camshaft inside the crankcase without removing the crankshaft.
Hereinafter, an embodiment of the invention will be described with reference to
As illustrated in
[Engine Body]
As illustrated in
As illustrated in
The bottom plate 19a is detachably attached to the lower end of the tubular portion 19c via a plurality of bolts B4. Specifically, the lower end of the tubular portion 19c is formed with a plurality of bolt fastening holes 19i through which the bolts B4 are inserted from below and the bottom plate 19a is formed with a plurality of bolt insertion holes 19j into which the bolts B4 are fastened from below. The bottom plate 19a is attached to the tubular portion 19c by fastening the bolts B4 to the bolt fastening holes 19i via the bolt insertion holes 19j. Conversely, the bottom plate 19a can be removed from the tubular portion 19c by releasing the fastening of the bolts B4 to the bolt fastening holes 19i.
As illustrated in
The crankcase cover 20 is detachably attached to the upper end of the crankcase body 19 via a plurality of bolts B. Specifically, a plurality of bolt insertion holes 20b, through which the bolts B1 are inserted from above, are formed in the peripheral portion of the crankcase cover 20 and a plurality of bolt fastening holes 19f into which the bolts B1 are fastened from above are formed in the upper end of the crankcase body 19. The crankcase cover 20 is attached to the crankcase body 19 by fastening the bolts B1 to the bolt fastening holes 19f through the bolt insertion holes 20b. Conversely, the crankcase cover 20 can be removed from the crankcase body 19 by releasing the fastening of the bolts B1 from the bolt fastening holes 19f.
As illustrated in
According to such cylinder unit 21, by preparing a plurality of types of cylinder unit 21 having different bore diameters, it becomes possible to provide an engine E having a different displacement simply by replacing the cylinder unit 21 while making the crankcase body 19 and the crankcase cover 20 common.
The cylinder unit 21 is detachably attached to the crankcase body 19 via a plurality of bolts B2 and B3. For example, when a plurality of bolt insertion holes (not illustrated) through which the bolts B2 are inserted from the front are formed at the rear end of the cylinder block 21b and a plurality of bolt fastening holes 19g for fastening the bolts B2 from the front are formed at the front end of the crankcase body 19, by fastening the bolts B2 to the bolt fastening holes 19g through the bolt insertion holes of the cylinder block 21b, the cylinder unit 21 can be attached to the crankcase body 19. Conversely, by releasing the fastening of the bolts B2 to the bolt fastening holes 19g, the cylinder unit 21 can be removed from the crankcase body 19.
However, in the engine body 1 of the embodiment, when the cylinder unit 21 is detachably attached to the crankcase body 19 via the plurality of bolts B2 and B3, the bolts B3 on the upper end side is fastened to the cylinder unit 21 from the inside of the crankcase body 19. Specifically, a plurality of bolt insertion holes 19h through which the bolts B3 are inserted from the inside of the crankcase body 19 toward the front are formed in the front end of the crankcase body 19 and a plurality of bolt fastening holes (not illustrated) for fastening the bolts B3 from the rear are formed at the rear end of the cylinder block 21b, and further the bolts B3 is fastened to the bolt fastening holes of the cylinder block 21b through the bolt insertion holes 19h of the crankcase body 19.
According to such a mounting structure of the cylinder unit 21, since it is not necessary to form a space for fastening the bolts B3 from the front side at least on the upper end side of the cylinder block 21b, the cylinder unit 21 can be attached to the crankcase body 19 without disturbing the external structure (for example, the cooling fin 21d) of the cylinder block 21b, and thus the cooling performance of the engine E can be improved.
[Valve Mechanism]
As illustrated in
A camshaft 25 includes a gear portion 25a which meshes with the timing gear 24 and is rotationally driven by the timing gear 24 at a speed reduction ratio of ½ and a cam portion 25b which alternately pushes the pair of lifters 27 according to the rotational drive of the gear portion 25a. When the cam portion 25b pushes the lifter 27, the other end of the corresponding rocker arm 29 is pushed through the push rod 30 and the intake valve 5 or the exhaust valve 6 connected to one end of the rocker arm 29 is opened. Conversely, when the pushing of the lifter 27 by the cam portion 25b is released, the intake valve 5 or the exhaust valve 6 is closed by the urging force of the valve spring 31.
The camshaft 25 of the embodiment is arranged below the cylinder base portion 21a of the cylinder unit 21. When the camshaft 25 is arranged as such, it is possible to access the inside of the crankcase body 19 from the top without removing the camshaft 25 by simply removing the crankcase cover 20 when maintaining the engine E.
However, in the arrangement configuration in which the camshaft 25 is arranged below the cylinder base portion 21a of the cylinder unit 21, that is, between the bottom plate 19a and the cylinder base portion 21a, particularly, in the arrangement configuration in which the cylinder base portion 21a of the cylinder unit 21 overlaps above the camshaft 25 as seen from the case opening portion 19b of the crankcase body 19, access to the camshaft 25 is blocked by the cylinder base portion 21a of the cylinder unit 21, and thus the maintainability and assembly of the valve mechanism 9 including the camshaft 25 may deteriorate.
As described above, the crankcase body 19 of the embodiment is formed by dividing the bottom plate 19a and the tubular portion 19c and the bottom plate 19a and the tubular portion 19c are detachably attached.
According to such a crankcase body 19, even when the cylinder unit 21 is not removed, it is possible to easily access the camshaft 25 by removing the bottom plate 19a from the tubular portion 19c. Therefore, the maintainability and assembly of the valve mechanism 9 including the camshaft 25 can be improved.
In the embodiment, since the crankcase cover 20 is also detachably attached to the crankcase body 19, it is possible to access the inside of the crankcase body 19 from the top by removing the crankcase cover 20 during maintenance of the engine E. In particular, when replacing the crankshaft 2, it is possible to easily replace the crankshaft 2 by removing the crankcase cover 20 and pulling out the crankshaft 2.
The embodiment described above can be appropriately modified, improved, and the like. For example, in the embodiment described above, the crankcase cover 20 is attachable to and detachable from the crankcase body 19, but the crankcase cover 20 may be formed integrally with the crankcase body 19.
At least the following matters are described in the specification. Although the constituent elements and the like corresponding to those of the embodiment described above are shown in parentheses, the invention is not limited thereto.
(1) An engine (engine E) which includes:
a crankcase body (crankcase body 19) including a bottom plate (bottom plate 19a) including a first crankshaft insertion hole (first crankshaft insertion hole 19d) and a tubular portion (tubular portion 19c) including a case opening portion (case opening portion 19b) on an opposite side to the bottom plate;
a crankcase cover (crankcase cover 20) including a second crankshaft insertion hole (second crankshaft insertion hole 20a) and covering the case opening portion of the crankcase body;
a crankshaft (crankshaft 2) which is inserted into the first crankshaft insertion hole and the second crankshaft insertion hole:
a cylinder base portion (cylinder base portion 21a) located inside the crankcase body;
a cylinder block (cylinder block 21b) located outside the crankcase body; and
a camshaft (camshaft 25) disposed inside the crankcase body and between the bottom plate and the cylinder base portion, where
the crankcase body has the bottom plate detachably attached to the tubular portion.
According to (1), since the bottom plate of the crankcase body is detachably attached to the tubular portion, by removing the bottom plate from the tubular portion during maintenance, it is possible to easily replace the camshaft inside the crankcase without removing the crankshaft.
(2) The engine according to (1), where
the crankcase cover is detachably attached to the crankcase body.
According to (2), the crankcase cover is detachably attached to the crankcase body. Therefore, even when the crankcase cover is removed, it is possible to access the inside of the crankcase. As a result, the maintainability is improved.
(3) The engine according to (1) or (2), where
the cylinder base portion overlaps with at least a part of the camshaft as seen from the case opening portion.
According to (3), the cylinder base portion overlaps with at least a part of the camshaft as seen from the case opening portion. Therefore, it is easier to replace the camshaft or the like by removing the bottom portion than removing the crankcase cover.
(4) The engine according to any one of (1) to (3), where
the cylinder base portion and the cylinder block form a cylinder unit (cylinder unit 21), and
the cylinder unit is detachably attached to the crankcase body.
According to (4), since the cylinder unit is detachably attached to the crankcase body, for example, the camshaft can be replaced by removing the crankcase cover and cylinder unit. Since the cylinder unit is detachably attached to the crankcase body, it is possible to provide an engine body with a different displacement by simply replacing the cylinder unit.
(5) The engine according to any one of (1) to (4), where
the engine includes a valve mechanism (valve mechanism 9),
the valve mechanism includes,
a timing gear (timing gear 24) fixed to the crankshaft,
the camshaft rotatably supported by the bottom plate of the crankcase body,
a pair of lifters (lifters 27) supported to be swingable on the bottom plate of the crankcase body.
a pair of rocker arms (rocker arms 29) which are supported to be swingable via rocker arm shafts (rocker arm shafts 28) and one end of which abuts against an intake valve (intake valve 5) or an exhaust valve (exhaust valve 6),
a pair of push rods (push rods 30) for connecting the pair of lifters to the other ends of the pair of rocker arms, and
a pair of valve springs (valve springs 31) for urging the intake valve and the exhaust valve in a closing direction, and
the pair of push rods are accommodated in a push rod accommodation portion (push rod accommodation portion 21e) formed in the cylinder block.
According to (5), the pair of push rods of the valve mechanism are accommodated in the push rod accommodation portion formed in the cylinder block. Therefore, it is possible to access the valve mechanism simply by removing the bottom plate when maintaining the engine. Since the push rod accommodation portion is formed integrally with the cylinder block, the number of parts can be reduced. As a result, the manufacturing cost can be reduced.
Kashima, Soji, Kiura, Toshiro, Tokubi, Kota
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Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Mar 30 2018 | Honda Motor Co., Ltd. | (assignment on the face of the patent) | / | |||
Aug 03 2020 | TOKUBI, KOTA | HONDA MOTOR CO , LTD | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 053832 | /0145 | |
Aug 05 2020 | KASHIMA, SOJI | HONDA MOTOR CO , LTD | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 053832 | /0145 | |
Aug 05 2020 | KIURA, TOSHIRO | HONDA MOTOR CO , LTD | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 053832 | /0145 |
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